Silver halide photographic emulsion sensitized with a heterocyclic compound containing 4-sulfur atoms

ABSTRACT

WHERE R1, R2, R3 and R4 individually represent hydrogen atoms or alkyl or aralkyl groups, and R1 and R3 may combine, respectively, with R2 R4 to form cycloalkyl groups. The sensitizing effect of the sensitizer compound can be improved by using the compound in combination with a compound which will liberate a thiosulfate ion, without increasing fog formation.   A novel sensitizer for silver halide photographic emulsions represented by the formula:

United States Patent [191 Ohi et al.

[451 Dec. 31, 1974 Related U.S. Application Data [63] Continuation-impart of Ser. No. 210,568, Dec. 2],

1971, abandoned.

[30] Foreign Application Priority Data Dec. 21, 1970 Japan 45-114544 [52] U.S. Cl. 96/107, 96/108 [51] Int. Cl. G03c 1/28 [58] Field of Search 96/107, 108

[56] References Cited UNITED STATES PATENTS 3,622,329 1 H1971 Huchstadt et al 96/107 3,656,955 4/1972 Ushimaru et al. 96/107 Primary Examiner-Norman G. Torchin Assistant Examiner-Won H. Louie, Jr.

Attorney, Agent, or Firm--Sughrue, Rothwell, Mion, Zinn & Macpeak 5 7] ABSTRACT A novel sensitizer for silver halide photographic emulsions represented by the formula:

where R R R and R individually represent hydrogen atoms or alkyl or aralkyl groups, and R and R may combine, respectively, with R R to form cycloalkyl groups.

The sensitizing effect of the sensitizer compound can be improved by using the compound in combination with a compound which will liberate a thiosulfate ion, without increasing fog formation.

20 Claims, 3 Drawing Figures BLANK (BUFFER ALONE) RECORDER MOLAR RATIO PATENTED 9 4 3, 857 71 1 RECORDER HG. l

v BLANK (BUFFER ALONE) v BLANK {BUFFER ALONE) FIG. 3

MOLAR RATIO CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part application of copending application Ser. No. 210,568, filed Dec. 21, 1971, now abandoned based on Japanese application No. 114544/70, filed Dec. 21, 1970, the priority of which is claimed.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a silver halide photographic emulsion and, in particular, to a silver halide photographic emulsion which has been chemically sensitized with a stable sulfur containing compound.

2. Description of the Prior Art In the manufacture of photographic emulsion, many chemical sensitization processes are known for the enhancement of photographic sensitivity. For instance, compounds containing one or more unstable sulfur atoms in the molecule, such as, e.g., sodium thiosulfate and thiourea derivatives, are known sulfur sensitizers, and certain reducing agents, such as, e.g., stannous chloride and hydrazine, are known reductive sensitizers. Some of these unstable sulfur containing com-- pounds and reductive compounds are believed to be contained in natural gelatin for photographic use.

Certain kinds of gold salts such as aurous thiocyanate also possess a chemical sensitization effect, and the technique of utilizing this effect is well known in the art as gold sensitization."

It is desired to further increase a sensitivity or speed of photographic silver halide emulsion. A heterocyclic compound having as a basic core the following formula:

has thus been proposed as a sensitizer in US. Pat. No. 3,656,955 issued to Ushimaru et al., which is characterized in the presence of five sulfur atoms in the ring (hereafter referred to as a S-sulfur containing compound). However, since the 5-sulfur containing heterocyclic ring is unstable, the 5-sulfur containing compound yields more readily a reactive sulfur atom which is inclined to impede proper sensitization. The inclipation of the 5-sulfur containing compound to react rapidly with the silver and produce uneven or irregular sensitization calls for special handling of the S-sulfur containing materials such as the use of diluted solutions, rapid stirring, etc., in the preparation of photo graphic emulsions. In addition, the 5-su1fur containing compound tends to form an undesired high level of fogging upon storage. The sufficiently high sensitivity without accompanying fog formation is not achieved with those known compounds.

SUMMARY OF THE INVENTION We have discovered that the compounds of the general formula:

S\ C /R3 S R wherein R and R and R and R individually represent hydrogen atoms or alkyl or aralkyl groups or, in combination, cycloalkyl groups, are very useful as sulfur sensitizer for any type of light sensitive silver halide photographic emulsions e.g., silver chloride emulsions, silver bromide emulsions, silver iodide emulsions and composite silver halide emulsions, irrespective of water washing or the lack of water washing and have thus accomplished the object of the present invention, i.e., to enhance the photographic sensitivity of light sensitive silver halide photographic emulsions,,with little or no increase in fogging.

The feature of the compounds of our invention which may be referred to as a 4-sulfur containing compour i d r esides in the hetero ring of the formula:

S c/ \C/ 5 f. s

Thus, the substituents of carbon atoms should not be limited to those mentioned. Any group which does not affect the sensitizing effect of out compound can be attached to the carbon atoms. Our compounds are charwhereas the S-sulfur containing compound must carefully be treated in the preparation of photographic emulsions not so as to give rise to undesirable local reaction with silver halide.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 shows a device for potentiometric titration.

FIG. 2 and FIG. 3 are a graphical representation of the molar ratio of silver nitrate to the sensitizer at varying potential levels, in which a sensitizer of this invention was compared with a similar sensitizer but having five sulfur atoms in the heterocyclic ring, as described hereinafter in a comparative example.

DETAILED DESCRIPTION OF THE INVENTION The chemical sensitizers represented by the above general formula can be exemplified by the following compounds, but the chemical sensitizers for use in the practice of the present invention are not restricted thereto,

Compound 1 Compound 2 Compound 3 Compound c c cH Compound 5 CH2 CH2 S----S\ /CH2-H2 CH2-CH2 S S VCHFQHZ Compound 6 CH CH2 s-- s CH2 cn CH o c CH2 x H CH2 5 CH CH2 The optimum amount of the sulfur sensitizer of the color developers, coating aids and other conventional above general formula to be added depends on the emulsion additives, and these materials may be added compound chosen, the silver halide used, the particle in a manner known to the art.

size of the silver halide, the temperature and time of While the sulfur sensitizer of the above general forripening and the pH and pAg of the silver halide emulmula is useful especially for sensitization of silver halsion, though, in general, the sensitizer compound may ide photographic emulsions prepared from inactive gelbe used in the amount within th ra f 0,01 mg t atin, it may also be used for sensitization of silver halide 100 mg per mole of silver halide. The smaller particle P g p emulsions in which at least a Portion of size, the lower temperature and the shorter time of ripthe Protectil/e colloid is a Photographicahy active gala" ening and the lower pH and higher pAg, the mu h more tin or other hydrophilic colloid, such as polyvinyl alcoamount is requested. When the sensitizer compound is 5 hol, polyvinyl pyrrolidone and other water soluble synused in combination with another sensitizer, or sensitizthetic resins well known in the art.

ers outside the scope of the invention, the amount m y The sulfur sensitizer of the present invention has the be a ler t an the lower limit of the above range and, characteristic that its sensitizing effect is especially enfor the case where the compound is used in eombinahanced in combination with a thiosulfate compound. tion with an antifogging agent, it may be used in a The amount 'of thiosulfate compounds is not critical. larger amount. Preferably 0.01 to 10 mole per mole of our S- The sulfur sensitizer of the present invention may be containing compound.

used in combination with a reductive sensitizer such as, Among the compounds represented by the above e.g., stannous salts or thiourea dioxide, with gold-, general formula, Compound 1 ca be synth ized by platinumand palladium salts such as, e.g., aurous thiothe process disclosed in Chem. Ber. 98, 1454 (1965), cyanate, or with sulfur containing compounds such as, Compounds 2 and 3 can be synthesized in accordance e.g., sodium thiosulfate and thiourea derivatives. In adwith the disclosure in Angew. Chem. 70,682 (1958), dition, it may be combined with a poly(oxyalkylene) Compounds 4 and 5 in accord with Acta. Chem. Scand. compound of a molecular weight of at least 300 or an 13,1031 (1959) and Compound 6 in accord with Acta. onium compound used. Examples of oniums are pyri- Chem. Scand. 12,890 (1958).

dinillm. SulfOnillm, The present invention will now be illustrated in The sulfur containing compound of the above gengreater d tail b th f ll in examples, eral formula in accordance with the present invention may be used not only in spectral sensitization but also EXAMPLE I in non-spectral sensitization and may be applied to monochromatic photographic emulsions, color photographic emulsions, X-ray photographic emulsions and graphic photographic emulsions.

The sensitizer of the present invention has no adverse effect on stabilizers, antifogging agents, film hardners,

Prior to beginning the chemical ripening of a high sensitivity, neutral process gelatino-silver iodobromide emulsion (Agl 5.0 mol%, AgBr 95.0 mol the emulsion was divided, in equal parts, into 5 specimens (Specimens A to E). To Specimens C to E were added methanolic solutions of Compounds 1, 2 and 3, respectively, and to Specimen B was added natural active gelatin. No addition was made to Specimen A. To each of the specimens there was then added an aqueous solution of 7.5 mg of chloroauric acid, 0.01 wt percent of aqueous solution was used, as a gold sensitizer and 150 mg of potassium thiocyanate per mole of silver halide. The emulsions were then subjected to chemical ripening at 50C for 60 minutes with stirring. The chloroauric acid used was the tetrahydrate. To 1 Kg of the chemically ripened emulsion there was added 30 mg of 3,3-diethyl-9-methylthiacarbocyanine bromide, 450 mg of chrome alum and 120 mg of saponin, and the emulsion was applied onto a cellulose triacetate film base and dried to provide a sensitive material (coating thickness: 14 microns). The material thus obtained was exposed one-fiftieth of a second with an optical wedge to a light source at a color temperature of 5,400K, developed at 20C for minutes using a developer of the following formation, fixed, washed with water and dried, and subjected to sensitometric analysis to obtain the data listed in Table 1.

As is evident from the Table l, marked sensitization effects were noticed for Specimens C, D and E. When the compound of the present invention was used the higher sensitivity without increasing fog formation was obtained in comparison with known active gelatin.

EXAMPLE 2 Prior to beginning chemical ripening of a fine grain positive, neutral process gelatino-silver chlorobromide emulsion (AgBr 58.0 mol AgCl 42.0 mol the emulsion was divided into three equal parts (Specimens A to C). A methanolic solution of Compound 4 was added to Specimen C, a natural sensitized gelatin to Specimen B (in amounts as listed in Table 2) and nothing was added to Specimen A. The three emulsions were then aged at 52C for 50 minutes and, thereafter,

there was added thereto, per 1 Kg of each emulsion 300 mg of 4-hydroxy-6-methyl-l ,3,3a, 7-tetrazaindene, 450 mg of chrome alum and 120 mg of saponin. Each emulsion was then applied onto a cellulose triaeetate base and dried to obtain a sensitive material (coating thickness: 12 microns). The materials were then exposed one-twentieth of a second with an optical wedge to a light source at a color temperature of 2,66()K, devel- .diethyl-S-methoxy-o-methylselena-Z-cyanine oped at 20C for 4 minutes with a developer of the following formulation, fixed, washed with water, dried and then subjected to a sensitometric analysis to obtain the data summarized in Table 2, which data indicates a marked sensitizing effect for the sensitizer of the present invention.

Prior to beginning of chemical ripening of a coupler in developer type reversal color, high sensitivity, neutral process gelatino-silver iodobromide emulsion (silver iodide 5.0 mol percent, silver bromide 95.0 mol percent), the emulsion was divided into equal five parts (SpecimensA to E). There was added to Specimen B a natural sensitized gelatin in amounts as listed in Table 3, and nothing was added to Specimen A. The five emulsions then had added thereto, per 1 mole of silver halide, 7.5 mg of chloroauroic acid tetrahydrate and 150 mg of sodium thiocyanate in solution in water, and the emulsions were subjected to chemical ageing at 50C for minutes with stirring. Each emulsion then had added thereto, per 1 Kg of emulsion, 30 mg of 1,3-

iodide, 450 mg of chrome alum and mg of saponin, was applied to a cellulose triacetate base and dried to obtain a sensitive material (coating thickness 8 microns). The material thus obtained was exposed one-twentieth of a second with an optical wedge to a light source at a color temperature of 5,400K, developed at 27C for 3 minutes and 30 seconds with a developer of the following formulation, fixed, washed with water, dried, and subjected to sensitometric analysis to obtain the data summarized in Table 3, which data indicates a remarkable sensitizing effect for the sulfur sensitizer of the present invention.

Developer N-methyl-para-aminophenol sulfate Anhydrous sodium sulfite Hydroquinone Potassium bromide Potassium thiocyanate 01% aqueous potassium iodide solution Sodium hydroxide Water to make I000 ml of solution Table 3 Spec- Sulfur Amounts added Relative Fog Gamma imen sensitizer mole of AgX sensitivity A 100 0.46 0.07 B Natural sensitized 10 g 1020 0.82 0.16 gelatin C Compound 55 mg 1020 0.87 0.13 D Compound 5 60 mg 1240 0.89 0.16 E Compound 5 65 mg 1100 0.86 0.13

EXAMPLE 4 Prior to beginning of chemical ripening of an ammonia process gelatin-silver iodobromide emulsion (AgI' 1.5 mol%, AgBr 98.5 mol%), the emulsion was divided into three equal parts (Specimens A to C), and to Specimens B and C there was added, respectively, Compounds 1 and 2, both in methanolic solution, in amounts as listed in the Table 4. To Specimens A was added, per mole of silver halide, 4.7 mg of sodium thiosulfate five pentahydrate and 1.2 mg of sodium dithiosulfatoauroate dihydrate Na Au(S O .2l-I O in aqueous solution, while to Specimen B these materials were added in an amount, per mole of silver halide, re spectively,-of4.7 mg and 3.2 X while to Specimen C there was added, per mole of silver halide, 1.2 mg of sodium dithiosulfatoauroate dihydrate alone. The emulsions were then subjected to chemical ripening at 50C for 70 minutes. The emulsion was then applied to a poly(ethylene terephthalate) film base and dried to obtain a sensitive material (coating thickness: 8 microns). The material thus obtained was exposed onetwentieth of a second with an optical wedge to a light source at a color temperature of 5,400K, developed at C for 4 minutes with a developer of the following formulation, and subjected, after fixing, washing with water and drying, to sensitometric analysis to obtain the data summarized in Table 4.

Developer that obtained in the case of Specimen A where the sulfur sensitizer was used alone. The marked effect shown in Examples 1 to 4 was, of course, Compounds 3 and 4.

EXAMPLE 5 Prior to beginning of chemical ripening of a negative color, high sensitivity, neutral process gelatin-silver l0 iodobromide emulsion (Agl 7.0 mol AgBr 93.0 mol the emulsion was divided into four equal parts (Specimens A to D).

However, it should be noted that our compound may be added to silver halide emulsion not only prior to the chemical ripening but also during the chemical ripening. In short, the chemical ripening may be conducted in the presence of our compound. 1

There was added, in amounts as listed in Table 5, a natural sensitized gelatin to the Specimen B, a natural sensitized gelatin and Compound 2 to Specimen C and Compound 2 to the Specimen D. Nothing was added to Compound A. To the four emulsions, there was then added, per mole of silver halide, 5.0 mg of chloroauroic acid tetrahydrate and 5.0 mg of potassium thiocyanate in aqueous solution, and the emulsions subjected to chemical ageing at 60C for 50 minutes with stirring. To 1 Kg of the emulsions there was added 180 mg of 3,3,9-triethyl-5,5'-dichlorothiacarbocyanine bromide, 300 mg of 4-hydroxy-6-methyl-l,3,3,7-tetrazaindene, 5 g of cyan coupler and 5 g of colored cyan coupler each described in Example of British Pat. No. 1,146,368, 450 mg of chrome alum and 120 mg of saponin were also added and the emulsions applied to a cellulose triacetate film base and dried to obtain a red sensitive color photographic light sensitive material (coating thickness: 5 microns).

The color sensitive material was exposed one onehundredth second, at a color temperature of 5,400K through an optical wedge to a red-colored light and subjected to color development in a conventional manner with a color developer of the following formulation.

Color developer N,N-diethyl-para-aminophenol sulfate 2.0 g N-methyl-para-am|nophenol sulfate 4.0 g Sodium sulfate E anhydrous sodium sulfrte 60.0 g Sodium carbonate monohydrate 50.0 g ydroqurnone 10.0 g Hydroxylamine hydrochloride g Sod um carbonate monohydrate 53.0 g Potassium bromide 1.0 g Sodium bromide 3.0 g Water to make 1000 ml of solution Water to make 1000 ml of solution (pH 10.8 t 1.0)

Table 4 Specimen Sulfur Amounts added/ Relative sen- Fog Gamma sensitizer mole of AgX sitivity A Na,S O;,.5H- O 4.7 mg 1.95 0.12

Na Au(S O,,) 1.2 mg 211 0 B Na,S,O;,.5H,O 4.7 mg

121 1.96 0.12 Na;,Au(S O .2H O 3.2 X 10mg Compound 1 C Na;Au(S,O .2H O 2 mg Compound 2 15 mg 1.93 0.13

In Specimens B and C, where a sulfur sensitizer of the present invention was used in comtination with sodium thiosulfate and/or sodium dithiosulfatoauroate, the sensitizing effect obtained was remarkably greater than The material was then bleached and fixed with bleaching and fixing solutions of the following formulations to eliminate undeveloped silver halides and reduced silver formed in development.

Bleaching solution I g 20 g Thus, there was obtained on each Sample a red positive image formed by the color coupler remaining in the film and a developed cyan negative image.

The color images obtained in Specimens A to D were subjected to sensitometric analysis to obtain the data summarized in Table 5, which indicates the remarkable sensitizing effect of the sulfur sensitizer of the present On the other hand, in the case ofthe 4-sulfur containing compound, the potential curve is almost the same as that of a blank, i.e., buffer solution. This means that no appreciable reaction of the 4-sulfur containing compound with silver ions occurred during the titration (titration rate for both samples: 5 minutes/one equivalent). Further, the solution containing the 4-sulfur containing compound of the present invention was allowed to stand. The gradual formation of silver sulfide was observed.

The gradual formation of silver sulfide as in the present invention is important for uniform sensitization of the emulsion. This is because chemical sensitization with a sulfur sensitizer proceeds in a heterogenous system, that is, the released sulfur ions from the sulfur sensitizer react with halide in the form of a heterogenous dispersion thereof to form silver sulfide, which silver sulfide is deposited on the surface of silver halide to sensitize silver halide. Accordingly, excessive reactivity of the sulfur sensitizer with silver halide causes uneven invention. deposition of silver sulfide on the surface of silver hal- Table 5 Specimen Sulfur sensi- Amounts added/ Relative sen Fog Gamma tizer Mole of AgX sitivity w A I00 0.33 0.03 B Natural scnsi- 10 g 1200 0.63 0.08

tized gelatin C Natural sensi- 10 g [350 0.67 0.07

tized gelatin Compound 2 50 g D Compound 2 75 mg 1500 0.65 0.07

COMPARATIVE EXAMPLE ide due to local occurrence of the formation of silver 1. Solutions of Compound 2 of the present invention and Compound 1 ofU.S. Pat. No. 3,656,955 Ushimaru et al. (each in methanol) were prepared (concentration 1/1000 mole/l) and maintained at C in a constant temperature bath. 4O

were maintained at 50C, using an automatic titration 45 buret to record the variations of potential on an automatic recorder.

The results are shown in FIGS. 2 and 3 in which the vertical axis shows electrical potential and the horizontal axis shows the molar ratio of silver nitrate to the 4- sulfur containing compound on the 5-sulfur containing compound. The change in potential as will be understood by one skilled in the art, corresponds to the change of the concentration of free silver ions. From these figures it can easily be seen that for the 5-sulfur containing compound of Ushimaru et al. the potential was small at low concentrations of silver nitrate at pH 7 and pH 9. This means that the compound of Ushimaru ct al immediately reacted with silver nitrate s ide.

From the above data, it can thus be seen that special care is not required in the present invention because of the moderate and appropriate reactivity ofthe 4-sulfur conatining compound, while the reactivity of the 5- sulfur containing compound with silver ions is so drastic that special care such as adding as a diluted solution, rapid stirring, etc., is required in the preparation of photographic emulsions.

2. This experimentation was conducted to compare the photographic effects of the S-sulfur containing compound of U.S. Pat. No. 3,656,955 Ushimaru et al. with the 4-sulfur containing compound of the present invention. 7 g g r a The experimentation was conducted using an emulsion obtained in accordance with the method described in Example 4 of the present specification. To separate but identical emulsions each of natural sensitized gelatin, Compound 1 of Ushimaru et al. and Compound 2 of the invention were added, respectively. The emulsions were then exposed as in Example 4 immediately after coating or after being subjected to an incubation test for 3 days at 50C under the relative humidities listed in Table 6 to determine the amount of fog which (removed tree silver ions) to form silver sulfide. would occur.

Table 6 Fog k Sensitizer Amount added] Relative After 3 days After 3 days mole of AgX Sensitiv- Immediately After Coating 50C 30%RH 50C RH ity A. Natural sensitized gelatin [5 g 0.05 0.26 0.29 B. Compound l of Ushimaru et al 5 mg NS 0.05 0.28 0.28 C. Compound 2 of the invention 30 mg NS 0.05 0.19 0.20

TABLE 6- Continued Fog at: Sensitizer Amount added/ Relative After 3 days After 3 days mole of AgX Sensitiv- Immediately After Coating 50C 3092 RH 50C 80% RH ity ' The amount of the sensitizers to he added was arranged to gain the same value of the relative sensitivity. that is. Compound 2 which had slow reactivity with silver ions as shown in 1) above was used in a six times amount as compared to Compound I of the prior art. As a decrease in fog is often more significant than an increase in sensitivity in the artv the greatest chance of fairly comparing both compounds would be given by leveling the relative sensitivity thereof.

" The conditions were set out under careful consideration of the practical use in the changeable climate in Japan and are helicved to be representative of inuse condition under high temperatures at low humidity and at high humidity.

As is shown in Table 6, the fog values for the samples 10 are the same immediately after coating but, after incubating the samples for 3 days, Samples A and B show an increase in fog. On the other hand, in Sample C containing the sensitizer of the present invention, the increase in fog is as compared to Samples A and B. In more detail, the increase in fog of Sample C was merely 014 after standing for 3 days at 50C under the relative humidity of 30 percent and 0.15 after standing for 3 days at 50C under the relative humidity of 80 percent, whereas, in Sample B, the increase in fog was 0.23 under both conditions. If the increase in fog, Afog, exceeds 2.0 a photographic emulsion will be unfit for the practical use even if it has a considerably high sensitivy From the results presented in the comparative study (1) and (2), it can be seen that the S-sulfur containing compound of the prior art harmed the photographic properties, i.e., increased fog during storage thereof, and that such a material cannot be equated to the 4- sulfur containing compounds of the present invention.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A photosensitive silver halide emulsion containing at least one compound of the formula:

wherein R,, R R and R each individually may be a hydrogen or a lower alkyl group.

R and R may combine with the bonded carbon of the sulfur containing ring and with themselves to form a cycloalkyl group containing up to six carbon atoms, including the carbon atom ofthe sulfur containing ring, and

Cit/s S/ 2 3. The photosensitive silver halide emulsion of claim 1 wherein said compound is CH3\C/ S---S\C/CH3 CH/ S/ Cll,

4. The photosensitive silver halide emulsion of claim 1 wherein said compound is 5. The photosensitive silver halide emulsion of claim 1 wherein said compound is S CH 6. The photosensitive silver halide emulsion of claim 1 wherein said compound is CH S--s 2 2 CH S s 8. The photosensitive silver halide emulsion of claim 1 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.

9. The photosensitive silver halide emulsion of claim 2 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.

10. The photosensitive silver halide emulsion of claim 3 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound. 11. The photosensitive silver halide emulsion of claim 4 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound. 12. The photosensitive silver halide emulsion of claim 5 further containing from about 0.01 to moles per mole of said compound of a thiosulfate compound. 13. The photosensitive silver halide emulsion of claim .6 further containing from about 0.01 to l0 moles per mole of said compound of a thiosulfate compound. 14. The photosensitive silver halide emulsion of claim 7 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound. 15. The pressure sensitive silver halide emulsion of claim 1 wherein said compound is used in combination 2 CH2\C/S-S\C/CH2' CH/ \S----- S/ \CH with another sensitizer and the amount of said compound is up to mg per mole of silver halide.

16. The photosensitive silver halide emulsion of claim 1 wherein said compound is used in combination with an antifogging agent and the amount of said compound is above 0.01 mg per mole of silver halide.

17. The photosensitive silver halide emulsion of claim 15 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.

18. The photosensitive silver halide emulsion of claim 16 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate com pound.

19. The photosensitive silver halide emulsion of claim 1 wherein said cycloalkyl group is one selected from the group consisting of a cyclobutyl group, a cyclopentyl group and a cyclohexyl group.

20. The photosensitive silver halide emulsion of claim 8 wherein said thiosulfate compound is one selected from the group consisting of sodium thiosulfate, aurous thiosulfate salt, thiourea derivatives and mixtures thereof. 

1. A PHOTOSENSITIVE SILVER HALIDE EMULSION CONTAINING AT LEAST ONE COMPOUND OF THE FORMULA:
 2. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 3. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 4. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 5. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 6. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 7. The photosensitive silver halide emulsion of claim 1 wherein said compound is
 8. The photosensitive silver halide emulsion of claim 1 further containing from about 0.01 to 10 moles per mole of said compound of a thiosuLfate compound.
 9. The photosensitive silver halide emulsion of claim 2 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 10. The photosensitive silver halide emulsion of claim 3 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 11. The photosensitive silver halide emulsion of claim 4 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 12. The photosensitive silver halide emulsion of claim 5 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 13. The photosensitive silver halide emulsion of claim 6 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 14. The photosensitive silver halide emulsion of claim 7 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 15. The pressure sensitive silver halide emulsion of claim 1 wherein said compound is used in combination with another sensitizer and the amount of said compound is up to 100 mg per mole of silver halide.
 16. The photosensitive silver halide emulsion of claim 1 wherein said compound is used in combination with an antifogging agent and the amount of said compound is above 0.01 mg per mole of silver halide.
 17. The photosensitive silver halide emulsion of claim 15 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 18. The photosensitive silver halide emulsion of claim 16 further containing from about 0.01 to 10 moles per mole of said compound of a thiosulfate compound.
 19. The photosensitive silver halide emulsion of claim 1 wherein said cycloalkyl group is one selected from the group consisting of a cyclobutyl group, a cyclopentyl group and a cyclohexyl group.
 20. The photosensitive silver halide emulsion of claim 8 wherein said thiosulfate compound is one selected from the group consisting of sodium thiosulfate, aurous thiosulfate salt, thiourea derivatives and mixtures thereof. 